While watching the DVD I noticed a rather odd thing.
During Radio Ga Ga, at 3 min 07 sec Roger is seen standing at the center of the stage. At 3 min 09 sec Roger is behind his drum kit. I didn't know Roger moves that quickly! :)
You're right. When Paul sings "all we hear is..." for the first time, the footage is from the second "all we hear is": You can see Roger sit down twice. Also, Paul does the same gesture both times.